1. Field of the Invention
This invention relates to a compressor, and more particularly to a compressor having a coolant jacket and pump, to be used for a general industrial compressor or a mechanical supercharger for an engine.
2. Description of the Prior Art
In case that a fluid is generally compressed or pressurized by using a compressor, the temperature of the fluid is increased. Consequently, the compressed fluid is cooled by an intercooler if the compressor is, for example, used as a mechanical type supercharger for an engine.
A conventional mechanical type supercharger is exemplarily disclosed in Japanese Utility Model Laid Open No. 62(1987)-78391, as shown in FIGS. 7 and 8. There, a housing is provided with an inlet 1a and an outlet 1b. A pair of rotors 2, 3 are rotatably supported by bearings in bearing housings 4, 5 at forward and rearward end portions thereof within the housing 1, respectively, and a pair of gears 6, 7 are provided at end portions of rotors 2, 3 and are engaged with each other. A jacket 1c is disposed within the housing 1 and bearing housings 4, 5, and an external cooling water circuit communicates with the jacket 1c. When the supercharger 8 in FIGS. 7, 8 is assembled in a system as in FIG. 6, the water passages in the jacket communicate with a heat exchanger (radiator) 9 and a water pump 10 in the fluid circuit.
Further, a conventional compressor which is exemplarily disclosed in Japanese Patent Laid Open No. 61-182420, as shown in FIG. 9, is used as a supercharger at an intake of an engine. A crankshaft 15 of an engine 11 is rotatably driven by the reciprocating movement of a piston 13 within a cylinder 12 via a connecting rod 14. At an upper portion of a combustion chamber 16 defined by the cylinder 12 and piston 13, a main inlet port 17, port 18 and outlet port 19 are provided.
A charge passage 22 separates from a main inlet passage 21 downstream of an air-flow meter 20 and is connected to the charge port 18 at the upstream end thereof. A supercharger 23 in charge passage 22 comprises an air pump of a vane type and pressurizes air from the main inlet passage 21. The supercharger 23 is driven by the crankshaft 15 via a transmitting member 24 such as a belt, chain etc. and the pressurized air is supplied to the charge port 18. A sub-intake valve 25 is opened and closed in synchronization with the crankshaft 15. The sub-intake valve 25 is opened so as to provide a charge between the end of the intake via the main intake valve 26 and the beginning of the compression stroke and is closed with a delay of a predetermined value as compared to the main intake valve. In the charge passage 22 downstream of the supercharger 23 are disposed an intercooler 27 for cooling the pressurized air, surge tank 28 for accumulating the pressurized air, a rotary type timing valve 30 driven in synchronization with the crankshaft 15 via a transmitting member 29 such as a belt, chain etc., and a charge valve 31.
When a conventional intercooler is used, a pressure loss is generated by the intercooler, a space is required for locating the intercooler and the fluid plumbing becomes complicated. In the supercharger 8 in FIG. 8, a jacket is interposed within housings 1, 4, 5 in order to circulate the cooling water. However, a water pump 10 (FIG. 6) is independently required and a space is required for the water pump 10 thereby increasing the cost therefor.
Furthermore, when the air temperature is increased upon compression by the supercharger without intercooling, the downstream plumbing could burn to the touch and it is impossible to decrease the plumbing diameter at the discharge side of the supercharger due to the increased volume of air. When connected to an engine, knocking of the engine is generated due to the high intake temperature and the volumetric efficiency of the engine is lowered by the increased air volume, thereby minimizing the improvement of the output.
When the intercooler 27 is utilized at a discharge portion of the supercharger 23 in order to decrease the temperature of the discharged air as shown in FIG. 9, there are the following problems.
The intercooler has to be located in the path of cooling air flow in an air-to-air type intercooler, so that the locating position is restricted, the plumbing becomes longer and complicated, and the intercooler becomes large in size.
In a water cooled type intercooler, a pump is required for circulating the water and the construction of the intercooler becomes complicated.